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Biomedical subjects

H Koike

Publications and source records attributed to H Koike.

At least 163 records · Page 9Linked to original sources
PubMed1994

5-HT1A receptor-mediated inhibition of N-type calcium current in acutely isolated ventromedial hypothalamic neuronal cells.

The effects of serotonin (5-hydroxytryptamine: 5-HT) and 5-HT1A agonist on voltage-gated calcium channels (VGCCs) in acutely isolated ventromedial hypothalamic (VMH) neuronal cells were studied using whole-cell configuration of the patch-clamp technique. 5-HT at 10 microM inhibited inward calcium current reversibly in 80% of cells. This inhibition was specific to N-type current. Because pindolol blocked the effect of 5-HT and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) mimicked the effect of 5-HT, the inhibitory effect of 5-HT appeared to be mediated via the 5-HT1A receptor. In the fura-2 fluorometry method, 8-OH-DPAT attenuated the [Ca2+]i increase induced by the depolarization stimulus of 50 mM K+. These results indicate that 5-HT suppresses Ca2+ entry through N-type channels in the VMH neurons via the 5-HT1A receptor and that the stimulating effect of 8-OH-DPAT on feeding behavior may be mediated by the blocking of Ca2+ entry through N-type channels.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1994

Anticoagulant and antiprotease activities of aprosulate sodium, a new synthetic polyanion, in human plasma and purified systems.

Aprosulate sodium, a new synthetic polyanion, was evaluated for anticoagulant/antiprotease activities in vitro. Aprosulate prolonged activated partial thromboplastin time (aPTT), Heptest and thrombin time (TT) with the sensitivity order of aPTT > Heptest > TT. Prothrombin time (PT) was hardly affected by the agent. Since these results indicated that inhibition of the intrinsic coagulation cascade was important for the anticoagulant activity of aprosulate, amidolytic assays were subsequently performed to characterize antiprotease activities of the agent in the common and intrinsic pathways. Aprosulate inhibited amidolytic activity of thrombin in the presence of heparin cofactor II, but was devoid of direct and antithrombin-mediated anti-factor Xa, and direct anti-factor XIIa activities. However, aprosulate was found to be a potent inhibitor of amidolytic activity of factor Xase (IXa/VIIIa). These data suggest that the direct anti-factor Xase activity of aprosulate primarily contributes to its anticoagulant activity in the intrinsic coagulation cascade.

Anticoagulants↗
PubMed1994

Effects of RS-2135, a novel class I antiarrhythmic agent, on sustained ventricular tachycardia after coronary embolization in conscious dogs.

To assess the ability of RS-2135, a novel class I antiarrhythmic agent to suppress ischemia-induced ventricular arrhythmias, we produced myocardial infarction (MI) by introducing a glass bead into the coronary artery of the dog (bead model). Ventricular arrhythmias after coronary embolization were as severe and long-lasting as those that occur after two-stage coronary artery ligation as described by Harris. RS-2135 (1.25 and 2.5 mg/kg intravenously, i.v.) suppressed sustained ventricular tachycardia (SVT) 24 h after coronary embolization in the bead model. The antiarrhythmic effects of i.v. administration of RS-2135 were more potent and more long-lasting than those of lidocaine (5 and 10 mg/kg i.v.), mexiletine (5 and 10 mg/kg i.v.), disopyramide (2.5 and 5 mg/kg i.v.), and flecainide (2.5 and 5 mg/kg i.v.). The antiarrhythmic effects of oral (p.o.) administration of RS-2135 were evaluated 48 h after coronary embolization. RS-2135 (10 mg/kg p.o.) was equipotent to flecainide (10 mg/kg p.o.) and twice as potent as disopyramide (20 mg/kg p.o.) and mexiletine (20 mg/kg p.o.). Onset of antiarrhythmic effects after p.o. RS-2135 was slower than that of other drugs. These data suggest that the bead model is as useful as the Harris model for evaluation of the antiarrhythmic potential of chemicals and that RS-2135, either i.v. or p.o., is effective against SVT after acute MI.

Administration, Oral↗
PubMed1994

Mathematical analysis and experiment on the corneal reflex test in spectacle wearers.

An experimental study and mathematical analysis of the corneal reflex test was undertaken in spectacle wearers. In the experimental study, photographs were taken of the corneal reflex through spectacles and the conversion ratios determined as measured in degrees/mm. In the mathematical analysis, the magnification effect of the lens was elucidated by three methods: geometrical analysis; real measurement of magnification factor; and ray tracing analysis. The real measurement of the conversion ratios was in good agreement with the conversion ratios determined by the three mathematical analyses. These results clearly showed that the corneal reflex test can be clinically useful even in wearers of spectacles.

Blinking↗
PubMed1994

Ultrasonographic findings of epididymal sarcoidosis.

We report a rare case of systemic sarcoidosis involving the epididymis. An irregularly shaped heterogeneous lesion was identified with ultrasonography in the left caput epididymidis. Microscopically, a number of noncaseating epithelioid cell granulomas were found in the epididymal tissue.

Adult↗
PubMed1994

Management of renal angiomyolipoma: a report of 14 cases and review of the literature. Is nonsurgical treatment adequate for this tumor?

14 patients with renal angiomyolipoma are presented. Two of them had tuberous sclerosis (TS) with synchronous bilateral and multiple tumors. Two other patients without TS also had multiple tumors in 1 kidney. More than half the patients were symptomatic (n = 8), 2 of them with spontaneous rupture of the tumor. Misdiagnosis, spontaneous rupture and tumor growth can be prevented by utilizing conservative, organ-sparing techniques. In cases of solitary kidneys with large and/or hemorrhagic angiomyolipoma, superselective arterial embolization is indicated.

Adult↗
PubMed1994

Effects of dihydropyridine Ca blockers on the renal function in nephrotic spontaneously hypertensive rat (SHR).

An animal model having both hypertension and reduced renal function was produced by intraperitoneal injection of puromycin aminonucleoside (PAN) in spontaneously hypertensive rat (SHR). Using this model, two different dihydropyridine Ca blockers, CS-905 and nicardipine, were compared with regard to the relationship between hypotensive effects and changes in renal function in a conscious state. A single oral administration of CS-905 or nicardipine at doses of 3 or 10 mg/kg produced a dose-dependent decrease in blood pressure and an increase in heart rate. Glomerular filtration rate (GFR) was decreased only at 10 mg/kg. However, there was a substantial difference between the two drugs with respect to the relationship between blood pressure and GFR. The decrease of GFR by nicardipine was observed when blood pressure was at the lowest level, while GFR decreased by CS-905 returned to the initial level when blood pressure reached a nadir. Percent decrease of GFR by CS-905 was significantly less than that by nicardipine although both agents produced almost the same degree of peak hypotension. These results suggest the decrease in GFR by Ca blockers depends not only on the degree of hypotension but other factors as well, such as the rate of blood pressure lowering. Despite the hypotension, both agents produced a marked natriuresis. Since the natriuresis was not accompanied by an increase in GFR, it was assumed that the natriuretic effect of Ca blockers stemmed from their tubular effects rather than glomerular ones.

Animals↗
PubMed1994

Production and epitope specificity of monoclonal antibody against mouse peptidylarginine deiminase type II.

Peptidylarginine deiminase catalyzes the conversion of arginyl residues in proteins to citrullyl residues in the presence of Ca2+. We described the preparation of monoclonal antibody (subclass type IgG1) specific to mouse peptidylarginine deiminase type II. The antibody had no effect on the enzyme activity and its specific epitope was localized in the eight-residue segment at the amino-terminal portion of the enzyme.

Amino Acid Sequence↗
PubMed1994

[Reduction in cellular immunity in diabetics receiving coronary artery bypass grafting].

We studied the changes in peripheral lymphocyte subsets, mitogen responsiveness, natural killer (NK) cell activity, and interleukin-2 (IL-2) production in patients with or without diabetes receiving coronary artery bypass surgery. Group I (GI): 9 diabetic patients comprising three on oral diabetics during therapy, two on insulin therapy, and four on alimentary therapy. Group II (GII): 12 non-diabetic patients (borderline diabetics excluded). age, amount of blood transfusion, number of grafts, aortic cross-clamp time (ACC), cardio-pulmonary bypass time (CPB), and operative time (OP) did not significantly differ between the groups. Lymphocyte subsets were measured using monoclonal antibodies and IL-2 production was measured by radio-immuno assay using IL-2 labeled with I125. All variables were measured the day before, the day after, 3 days after and 7 days after the operation. The number of lymphocytes and their subsets (CD3+, CD+, CD8+, 4/8 ratio, IL-2R+) did not significantly differ between the groups, but in GI patients, the number of OKIa1 positive lymphocytes were significantly lower than in GII the day before and 7 days after the operation. II-2 production on the day after the operation was significantly (p < 0.05) reduced from the preoperative level in both groups. On 3 days, there was a significant difference (p < 0.05) between the two groups: IL-2 production in GI (3.1 +/- 2.6 U) was remarkably lower than in GII (6.6 +/- 4.0 U). IL-2 production in GII was significantly correlated to the number of CD4 positive lymphocytes, but this was not true in GI. Mitogen responsiveness to stimulation with PHA was not significantly different between the groups. NK cell activity on the first postoperative day was significantly reduced (p < 0.01) in the both groups, but there was no difference between the groups. The % change in IL-2 production (%IL-2) in GII on 3 days after the operation was significantly correlated to the amount of blood transfusion (r = -0.7, p = 0.0077) but that in GI was not. %IL-2 was not significantly correlated to ACC, CPB, OP, or age in both groups. This study clearly showed that diabetics who underwent coronary artery bypass surgery suffered depression of cellular immunity, in particular, IL-2 production, which might be a key factor in cellular immunity. It showed a decrease in helper T lymphocyte function after surgery, implying postoperative immunodeficiency in diabetics.

Aged↗
PubMed1994

Effect of the platelet activating factor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride on endotoxin-induced hypotension and hematological parameters in rats.

The intravenous administration of endotoxin to anesthetized rats resulted in different hypotensive reactions depending on its dosage. More than 10 mg/kg of endotoxin induced biphasic hypotension; the first phase consisted in a small and transient depression (approximately 15 mmHg) of mean arterial pressure occurred within 1 min after the administration, and the second phase was a large and sustained depression (maximally 40 mmHg) observed from 1 h after the injection. At less than 3 mg/kg of endotoxin, the first phase of hypotension did not occur whereas the second phase of hypotension was observed. Pre-treatment or post-treatment with a specific platelet activating factor (PAF) antagonist, SM-12502 ((+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl, CAS 119383-00-5) inhibited the second phase of endotoxin (1 mg/kg)-induced hypotension. In addition, post-treatment with another PAF antagonist, (3-(4-(2-chlorophenyl)-9-methyl-6H-thieno (3,2-f) (1, 2,4)-thiazolo-phenone) also inhibited the second phase of hypotension. Blood PAF-like substance level, measured by the PAF radioimmunoassay, slightly increased at 1 min after administration of endotoxin (30 mg/kg). At 90 min after the injection, endotoxin (1 mg/kg) induced a significant increase of PAF-like substance level.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effects of CS-905, a novel dihydropyridine calcium channel blocker, on arterial pressure, renal excretory function, and inner medullary blood flow in the rat.

CS-905 is a dihydropyridine calcium channel antagonist which stands out for its prolonged hypotensive effect, and which is currently under investigation for the treatment of hypertension. The aim of the current series of studies was to investigate the effects of CS-905 on renal function in relation to its effects on arterial pressure. In anesthetized spontaneously hypertensive rats (SHR), intravenous bolus injection of CS-905 reduced mean arterial pressure (MAP) in a dose-dependent fashion. In parallel, there was a dose-related increase in urine flow (V), sodium excretion (UNaV), renal plasma flow (RPF), and glomerular filtration rate (GFR). In chronically cannulated unanesthetized SHR, single-dose CS-905 by gavage produced a sustained reduction in MAP, a significant increase in V and UNaV, no effect on RPF, and an increase in GFR. Continuous intrarenal infusion of CS-905 in anesthetized normotensive Munich Wistar rats at doses that did not affect MAP caused a marked diuresis and natriuresis, without affecting RPF or GFR. To determine whether the diuretic and natriuretic effects of CS-905 were mediated by changes in inner medullary blood flow, the effect of CS-905 on vasa recta blood flow (Qvr) was studied by fluorescent videomicroscopy in anesthetized normotensive Munich Wistar rats during continuous intrarenal infusion. At low infusion rates, CS-905 was diuretic and natriuretic while increasing Qvr. With a high infusion rate, although the diuretic and natriuretic effects of CS-905 were maximal, Qvr decreased. These findings suggest that the diuretic and natriuretic effects of CS-905 are dissociated from and cannot be accounted for by changes in RPF, GRF, or Qvr, and are most likely secondary to a direct action of CS-905 on renal tubule handling of sodium and water.

Anesthesia↗
PubMed1994

[Results of reoperation for prosthetic dysfunction in the mitral position].

We analyzed surgical results of 91 patients who underwent re-mitral valve replacement (reMVR) for valve morbidity between January 1981 and March 1994 in an attempt to draw some therapeutic guidelines. The study population consisted of 38 men and 53 women, ages 32-73 (mean 52 +/- 10) years. The causes of valve morbidity were structural deterioration in 71 patients, nonstructural dysfunction manifested by paravalvular leakage in 5 valve thrombosis in 7 and prosthetic valve endocarditis in 8. Twelve of ninety-one patients (13.2%) died postoperatively in the hospital. All the patients were divided into the survivors (n = 12) and the nonsurvivors (n = 79). Mean right atrial pressure, extracorporeal circulation time, concomitant coronary artery bypass grafting, and application of intra-aortic balloon pumping were significantly different between the groups. Twenty preoperative and intraoperative variables were analyzed by means of univariate and multivariate analysis. By univariate analysis, male gender, NYHA IV, history of congestive heart failure, renal insufficiency and prosthetic valve stenosis were related to a higher incidence of hospital death. Multivariate analysis revealed that male gender and NYHA IV were risk factors in reMVR, and indicated no differences in intraoperative parameters between survivors and deaths. It is recommended to examine patients with bioprostheses thoroughly and to perform early elective reMVR before a patient develops NYHA IV.

Adult↗
PubMed1994

[A case of renal liposarcoma].

A-48-year-old male was admitted to our hospital with a right renal tumor. He received radical nephrectomy immediately. Histological examination of surgical specimen revealed renal liposarcoma, which consisted of mixed type of pleomorphic and well differentiated subtypes. Multiple tumorous lesions were scattered in the renal parenchyma. He has been alive without disease for 2 years and 7 months after surgery. Only 23 cases of renal liposarcoma have been reported in Japan.

Humans↗
PubMed1994

Biological effects of the new platelet-activating factor receptor antagonist (+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one hydrochloride.

SM-12502 ((+)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl, CAS 119383-00-5) inhibited platelet-activating factor (PAF)-induced aggregation of rabbit and human platelets with IC50 values of 2.3 mumol/l and 4.7 mumol/l, respectively, but did not inhibit platelet aggregation induced by adenosine diphosphate, collagen, thrombin, arachidonic acid, U46619 (a thromboxane A2 agonist) or Ca2+ ionophore A23187 at concentrations up to 400 mumol/l. SM-12502 competitively antagonized 3H-PAF binding to rabbit platelets with an IC50 of 1.0 mumol/l. In contrast, the anti-PAF activity of the optical isomer SM-12501 ((-)-cis-3,5-dimethyl-2-(3-pyridyl)thiazolidin-4-one HCl) was much weaker and its IC50 was more than 100 mumol/l. SM-12502 prevented PAF-induced death in mice with ID50 values of 4.8 mg/kg (i.v.) or 68.6 mg/kg (p.o.). In guinea pigs, SM-12502 inhibited PAF (0.1 micrograms/kg)-induced hemoconcentration with ID50 values of 1.9 mg/kg (i.v.) or 40.2 mg/kg (p.o.). In addition, SM-12502 inhibited PAF (10 ng/kg)-induced hypotension in rats with ID50 values of 2.0 mg/kg (i.v.) or 6.5 mg/kg (p.o.). The in vivo effects of SM-12501 were much weaker. Orally administered SM-12502 showed rapid absorption and a long duration of pharmacological activity in rats. SM-12502 afforded dose-dependent protection against anaphylactic death in mice with ID50 values of 18.4 mg/kg (i.v.) and 136 mg/kg (p.o.). It also inhibited endotoxin (E. coli 0.55:B5, 60 mg/kg)-induced death in mice, with ID50 values of 119 mg/kg (i.v.) and 182 mg/kg (p.o.).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗
PubMed1993

Characterization of cysteine residues of mitochondrial ADP/ATP carrier with the SH-reagents eosin 5-maleimide and N-ethylmaleimide.

The effects of the membrane-impermeable fluorescent sulfhydryl reagent eosin 5-maleimide (EMA) and the membrane-permeable sulfhydryl reagent N-ethylmaleimide (NEM) on ADP transport via the ADP/ATP carrier and their labeling sites in the carrier were studied in bovine heart submitochondrial particles. Of the 4 cysteine residues in the carrier, EMA labeled Cys159 very rapidly, Cys56 slowly, and Cys256 very slowly and did not label Cys128. Its labeling of Cys159 was associated with inhibition of the ADP transport, suggesting that the peptide segment containing Cys159 is involved in the transport of adenine nucleotides. In contrast to the very rapid binding of EMA to Cys159, NEM bound to Cys56 more slowly and labeled Cys159 and Cys256 much more slowly. Like EMA, it did not react with Cys128. The labeling of Cys56 with NEM also inhibited ADP transport. From these results, the locations of these cysteine residues in the ADP/ATP carrier are discussed in relation to the transport of adenine nucleotides mediated by the ADP/ATP carrier.

Animals↗
PubMed1993

Effect of fibroblast growth factors on calcium currents in acutely isolated neuronal cells from rat ventromedial hypothalamus.

Three types of voltage-gated calcium currents (VGCCs) were recorded using the whole-cell configuration of the patch-clamp technique in acutely isolated neurons from rat ventromedial hypothalamus. They consist of a transient low-threshold current, a nicardipine-sensitive L-type current and an omega-CgTX sensitive N-type current. Basic fibroblast growth factor (bFGF) at a concentration of 10-100 ng/ml augmented the L-type current immediately after the addition to the bath. However, the effect was observed only in 29% of the cells tested. Acidic fibroblast growth factor did not affect the VGCCs in the cells. It is suggested that part of the neurotrophic effects of bFGF are attributable to the increase in the L-type calcium current.

Animals↗